The phenyl butenoid dimer has an NGF-like action (one of the actions of the neurotrophic factor) effective as a prophylaxis and/or treatment of neurogenic diseases such as brain ischemia, Alzheimer's disease, Parkinson's disease and Huntington's disease.
Herein, “NGF” means an abbreviation for “Nerve growth factor” which is a cytokine peptide factor showing differentiation/growth activities of nerve tissues (“IWANAMI's BIOLOGY DICTIONARY, 4th Edition,” 1998, Iwanami Shoten, Publishers).
Senile dementia (mental deterioration) is becoming a more common social problem with the rapid aging of society. As types of senile dementia, Alzheimer's disease and cerebrovascular dementia are known.
For Alzheimer's disease, treatments by acetylcholinesterase inhibitors or the like have been tried, but are limited, and there is no effective therapy yet because of unclear pathogeny and advanced disease. Thus, development of an NGF production promoter or an NGF-like action substance is strongly desired in order to prevent and treat dementia, because the NGF is needed for growth of neurocytes, promotion of neurite formation/extension, maintenance of activity and protection of neuronal cell death.
In addition, BIOCHEMISTRY DICTIONARY, 3rd Edition (Editors: Kazutomo Imahori, Tamio Yamakawa), p. 711, Tokyo Kagaku Dojin (1998) (NonPatent Document 1) discloses that since this NGF is a peptide factor which acts on cholinergic neurons of Meynert's nucleus basalis in a basal forebrain as a neuron group which experiences remarkable loss particularly with Alzheimer's disease, its direct application for treatment of Alzheimer's disease is being tried. However, the NGF cannot pass through the blood-brain barrier as it has a high molecular weight (polypeptide), and hence it is intraventricularly administered, resulting in many problems.
Thus, the present inventors previously found that the phenyl butenoid dimer (substituted cyclohexene) which is a solvent-extracted concentrate from an Indonesian zingiberaceous plant (Java ginger) showed an NGF-like action as one action of neurotrophic factor-like actions, and proposed a healthy composition containing an extract which is a concentrate of a liquid extracted from Java ginger in Japanese patent publication No. 2010-90053 A (Patent Document 1).
As components of the zingiberaceous plant commonly used in Japan, gingerol, curcumin, curcumene, etc., are known as disclosed in Medicinal Food Pharmaceutical Science Handbook (Editors: Isao Kitagawa, Masayuki Yoshikawa), pp. 54 and 122, Kodansha Ltd. (2005)(Non Patent Document 2), but the phenyl butenoid dimer (1) and monomer (2) respectively represented by the following chemical formulas have not been recognized.

Meanwhile, in the Java ginger, two components, the above-mentioned monomer and dimer have been recognized as disclosed in Synopsis on 3rd Symposium on Pharmaceutical Food Science (Megumi Nakai, et al.), p. 65 to 67, The Pharmaceutical Society of Japan, Division of Natural Medicines (2009) (Non Patent Document 3).
Since a content of the phenyl butenoid dimer in the solvent-extracted Java ginger extract is extremely low compared to that of the monomer showing no NGF-like action, an intake of the extract should be increased to exert the NGF-like action at an effective level.
In addition, Japanese patent publication No. 2003-313116 A (Patent Document 2) discloses that the phenyl butenoid dimer has platelet-activating factor antagonism and tyrosinase activity-inhibiting action. Furthermore, Japanese patent publication No. 2003-306438 A (Patent Document 3) discloses that the phenyl butenoid dimer has chemokine expression-inhibiting action.
However, all of the Patent Documents 1 to 3 and the Non Patent Document 3 do not disclose nor suggest a trial to increase the content of the phenyl butenoid dimer in the Java ginger extract.